She told i100.co.uk she was "completely overwhelmed" by the reaction to her two books, Secret Garden and Enchanted Forest, which take the first and second spots respectively. Secret Garden is also number one in the UK.
When I initially pitched my idea for a colouring book for grown-ups to my editor in 2012 there was a bit of a silence - colouring in for adults wasn't a trend back then and we had no idea how big, if any, the audience for something like this would be.
My aim was to just make a book that I myself would love, then hope a few other people would feel the same and buy it. To see so many people around the world buying the books and making adult colouring a global trend, it just amazes me.
Basford isn't the only author of colouring books for adults enjoying success. Five of the 10 top selling books on Amazon in Britain are colouring books for adults.